What to do with starsan after keg purge

[Crafty_Brewer]

Well since you're the OP, how did you push it anyway?

If it's just about saving money, then sanitize the keg with a quart of starsan, pour that out to another container for re-use, and purge the empty keg with fermentation gas.

I pushed with tank Co2 and created the thread to ask people’s process on saving the starsan for later, which I plan on storing it in a Home Depot bucket for future use.

I try to save money and reduce waste where I can, but without negatively impacting the quality of the final product or adding significantly to the time & effort spent.

 

[Tony B]

I keep a dedicated keg full of starsan solution. I let the co2 from fermentation push it into my packaging keg. Then swap them and push it back into the starsan keg. A quart or more will blow off during fermentation. I also use the starsan keg to flush out my beer lines and fill my spray bottle. Before I start a new batch of beer, I top off the keg with RO water and a little more starsan. Check the ph to make sure it’s 3.0 or lower.

 

[BasementArtie]

I wonder if single use starsan & fermentation purge or reusing starsan and pushing out with co2 is cheaper?

Last time I checked it was $23 to swap my 20# tank, and it looks like 32 oz of Starsan is going for $30.

The starsan would be $0.94/5 gallons, and the co2 would be maybe $0.60 to push 5 gallons if you believe chatGPT estimating being able to push about 40 kegs not including carbonation.

It might be cheaper to push the starsan with Co2 instead of using fermentation gas if it means the fermentation gas spoils the re-use of starsan due to picking up flavors.

Something I never considered with this tbh. That's actually really interesting.

One of the reasons I use natural purging CO2 is because apparently pure food grade CO2 isn't 100% CO2 it has the smallest proportion of O2 in it (don't know how true that is).

But any I'm probably going to email Five Star to ask if odors form fermentation affect the effectiveness of Starsan if the pH is still correct and the liquid still clear.

If the Starsan is not effective then I will switch to tank purging.

 

[Crafty_Brewer]

I keep a dedicated keg full of starsan solution. I let the co2 from fermentation push it into my packaging keg. Then swap them and push it back into the starsan keg. A quart or more will blow off during fermentation. I also use the starsan keg to flush out my beer lines and fill my spray bottle. Before I start a new batch of beer, I top off the keg with RO water and a little more starsan. Check the ph to make sure it’s 3.0 or lower.

Nice, another nod to topping off with more StarSan; that was one of the big process points holding me back that I’m going to integrate.

I’m probably going to use a Home Depot bucket for now because it’s cheap, but do you have any issues with the Starsan corroding the keg over time, or leaving a film?

 

[Crafty_Brewer]

Something I never considered with this tbh. That's actually really interesting.

One of the reasons I use natural purging CO2 is because apparently pure food grade CO2 isn't 100% CO2 it has the smallest proportion of O2 in it (don't know how true that is).

But any I'm probably going to email Five Star to ask if odors form fermentation affect the effectiveness of Starsan if the pH is still correct and the liquid still clear.

If the Starsan is not effective then I will switch to tank purging.

lol, I wonder if this thread will be responsible for tank purges to become more popular than fermentation gas purges. Purging with fermentation gas had seemingly gotten super popular.

 

[mac_1103]

apparently pure food grade CO2 isn't 100% CO2 it has the smallest proportion of O2 in it (don't know how true that is)

It's true. The question is how important is it? There are threads.

 

[BasementArtie]

I keep a dedicated keg full of starsan solution. I let the co2 from fermentation push it into my packaging keg. Then swap them and push it back into the starsan keg. A quart or more will blow off during fermentation. I also use the starsan keg to flush out my beer lines and fill my spray bottle. Before I start a new batch of beer, I top off the keg with RO water and a little more starsan. Check the ph to make sure it’s 3.0 or lower.

Do ever notice fermentation aromas in the Starsan?

 

[mashdar]

Something I never considered with this tbh. That's actually really interesting.

One of the reasons I use natural purging CO2 is because apparently pure food grade CO2 isn't 100% CO2 it has the smallest proportion of O2 in it (don't know how true that is).

But any I'm probably going to email Five Star to ask if odors form fermentation affect the effectiveness of Starsan if the pH is still correct and the liquid still clear.

If the Starsan is not effective then I will switch to tank purging.

IMO you can purge with ferm gas, or purge via displacement, but both is redundant.

I'm skeptical that you can approach the theoretical endpoint of ferm gas purging when using real-world tubing and fittings. Starting with an already-low starting O2 concentration (by using the first 5 gallons of CO2 to displace star san) will land you at the same end state.

I think ferm gas purging is superior, but the difference may be minor. Down sides of displacement purging are:
- small O2-rich headspace remains in keg
- ~8ppm O2 in residual star san solution
- CO2 is not free
- may require increased human time to monitor
- possible CO2 source contamination

The biggest down side to ferm gas purging is having to get the keg ready on brew day while being a lazy human.

 

[Tony B]

Nice, another nod to topping off with more StarSan; that was one of the big process points holding me back that I’m going to integrate.

I’m probably going to use a Home Depot bucket for now because it’s cheap, but do you have any issues with the Starsan corroding the keg over time, or leaving a film?

I have used this system for 6-8 months now and have had no issues. I only use RO water and check the ph. Mine is usually a bit under 3.0. In the high 2’s.
I’m using the most beat up of the used kegs I own. It still has the original dip tube and seals. I have heard that leaving the acidic solution in there will corrode it. At some point, I will dump the entire keg and inspect it. I have been fortunate enough to find used kegs for $20-$40 each, so I’m not too worried about replacing it when the time comes and this keeps me from dumping a lot of perfectly good starsan.
When I am brewing, I usually mix about a gallon or two of fresh starsan in my fermenter and shake it around every 30 minutes or so as I’m brewing. Then I’ll pour some of that into a pot or bucket to sanitize transfer tubing etc, and then dump whatever is left when the brew day is done.

 

[DuncB]

I've stopped noticing a smell in the Starsan I don't sniff it

 

[Crafty_Brewer]

It's true. The question is how important is it? There are threads.

Probably less important than food grade vs industrial grade Co2. I use whatever my local welding shop gives me when doing a 20# tank swap.

 

[mac_1103]

GRADE	PURITY	OTHER GASES
Research	99.999%	0.001%
Super-critical Fluid	99.998%	0.002%
Laser	99.95%	0.05%
Anaerobic	99.95%	0.05%
Beverage	99.9%	0.1%
Food	99.9%	0.1%
Bone Dry	99.8%	0.2%
Medical	99.5%	0.5%
Industrial	99.5%	0.5%

"Other gasses" include but are not entirely oxygen.

 

[Crafty_Brewer]

GRADE	PURITY	OTHER GASES
Research	99.999%	0.001%
Super-critical Fluid	99.998%	0.002%
Laser	99.95%	0.05%
Anaerobic	99.95%	0.05%
Beverage	99.9%	0.1%
Food	99.9%	0.1%
Bone Dry	99.8%	0.2%
Medical	99.5%	0.5%
Industrial	99.5%	0.5%

"Other gasses" include but are not entirely oxygen.

Cool. I’ll call it good enough for what I can get my hands on.

 

[day_trippr]

Note those bin specs are "worst case"....

 

[Brockness Monster]

GRADE	PURITY	OTHER GASES
Research	99.999%	0.001%
Super-critical Fluid	99.998%	0.002%
Laser	99.95%	0.05%
Anaerobic	99.95%	0.05%
Beverage	99.9%	0.1%
Food	99.9%	0.1%
Bone Dry	99.8%	0.2%
Medical	99.5%	0.5%
Industrial	99.5%	0.5%

"Other gasses" include but are not entirely oxygen.

Pretty sure the Anaerobic entry is gases from fermentation. If that is the case, you are not really avoiding that much more oxygen by purging with it, but it is free and I will be doing it now that I have the capability.

 

[mac_1103]

Pretty sure the Anaerobic entry is gases from fermentation.

What gives you that idea? It's commercial CO2 intended for creating anaerobic environments.

 

[mac_1103]

Note those bin specs are "worst case"....

Exactly. These are minimum specifications for labeling each of the grades. Higher grades require more rigorous testing with more expensive methods.

 

[Brockness Monster]

What gives you that idea? It's commercial CO2 intended for creating anaerobic environments.

Such as?

 

[mac_1103]

Such as?

Propagating obligate anaerobic organisms. In practice, we just used the medical grade stuff instead of ordering two different grades. But I never really did it at scale. I suppose there are other industrial applications where such an environment might also be useful.

 

[Brockness Monster]

Hmm, good example. I would have thought industrial or medical grade would have been fine. I know Fermentation CO2 is not 100% like people assume. In fact, it is around 95% but that other 5% is mostly atmospheric H2O and Ethanol. There is a very small amount of VOCs as well, but I can't seem to find a study that gives me numbers. The search continues.

Edit: all of the above is slightly off-topic of course and, but I just read the following study about fermentation in a vacuum, and also CO2 concentration effect on production of VOCs. Crazy stuff

https://pmc.ncbi.nlm.nih.gov/articles/PMC10124126/

 

[mac_1103]

In fact, it is around 95% but that other 5% is mostly atmospheric H2O and Ethanol.

Of course, those aren't gasses. But now you've got me wondering what the spec is for water in commercial CO2.

 

[day_trippr]

It's gotta be near zero to not freeze up cylinder valves...

 

[crazyjake19]

I push the StarSan from keg to keg to keg. I mixed up the initial batch with RO water and it stays effective for a long time. Every few transfers I check the pH to make sure it's still good.

I mix up separate 1-gallon batches to fill my spray bottles.

 

[T Murph]

Wow. IMO purging pre-cleaned kegs with fermentation gas is a big cost savings. I wait until the fermenting vessel is at high krausen before beginning to purge empty kegs. Then I connect a hose from the gas in side of the fermenter, (same port as the blow off hooks to) with the other end connected to the out post of a 1.6 gal Torpedo Keg that is filled approximately half full of a fresh StarSan solution. This step aids in sanatising the fermentation gas (co2). Next I connect a line from the gas port of the Torpedo Keg to the beer out port of the 1st Sanke Keg coupler with another line going from the gas port of the 1st keg to the beer out port of a 2nd Sanke Keg. And a line from there with a spunding valve set at 5 psi to a blow off bottle with StarSan. I usually do 2 or 3 kegs at a time, and I will let the blow off go all day, sometimes longer. This ensures that most all of the o2 gets removed.

As for how long the solution last, one month is a good rule of thumb but as long as it is kept in a clean non-porus container with a lid it will hold up longer. If it becomes cloudy and has debri in it, or doesn't creat bubbles when shaken up toss it out and make a new batch. I reccommend using a good quality food grade bucket to store it in.

This came as a shock to me, but a while back I dumped 5 gallons of used StarSan solution in my electric boil kettle. I left it in there over night. When I dumped it out to my surprised it had cleaned the heating element. I will do that again when it gets coated with residue.

 

[T Murph]

It's gotta be near zero to not freeze up cylinder valves...

I read that it is .02 percent. Upon reading that, it concerned me because in addition to purging kegs, I also carbonate fresh beer using fermentation gas. Fortunately I have not had any issue from that practice, however I am currently avoiding doing so.

I will add something else that I recently learned. Industrial Oxygen and Medical Oxygen are the exact same oxygen. The are pumped from the very same huge tank. Only difference, they do exercise a bit more precaution with medical to ensure a sanitary environment. I have a nephew who owns two welding supply businesses and he assured me there is no difference between the two. I have been using Medical Oxygen to oxygenate brews for years only to learn Industrial Oxygen is the same. Makes ZERO sense to me that anyone off the street can go to a welding supply store and buy oxygen. But if you want Medical Oxygen you first have to have a perscription by a doctor and they will not give you one unless you are about to die. Plus Industrial Oxygen only cost about a fourth of what medical cost.

 

[BasementArtie]

Wow. IMO purging pre-cleaned kegs with fermentation gas is a big cost savings. I wait until the fermenting vessel is at high krausen before beginning to purge empty kegs. Then I connect a hose from the gas in side of the fermenter, (same port as the blow off hooks to) with the other end connected to the out post of a 1.6 gal Torpedo Keg that is filled approximately half full of a fresh StarSan solution. This step aids in sanatising the fermentation gas (co2). Next I connect a line from the gas port of the Torpedo Keg to the beer out port of the 1st Sanke Keg coupler with another line going from the gas port of the 1st keg to the beer out port of a 2nd Sanke Keg. And a line from there with a spunding valve set at 5 psi to a blow off bottle with StarSan. I usually do 2 or 3 kegs at a time, and I will let the blow off go all day, sometimes longer. This ensures that most all of the o2 gets removed.

As for how long the solution last, one month is a good rule of thumb but as long as it is kept in a clean non-porus container with a lid it will hold up longer. If it becomes cloudy and has debri in it, or doesn't creat bubbles when shaken up toss it out and make a new batch. I reccommend using a good quality food grade bucket to store it in.

This came as a shock to me, but a while back I dumped 5 gallons of used StarSan solution in my electric boil kettle. I left it in there over night. When I dumped it out to my surprised it had cleaned the heating element. I will do that again when it gets coated with residue.

So do you ever experience the hoppy aroma in the Starsan evacuated from the kegs?

 

[T Murph]

So do you ever experience the hoppy aroma in the Starsan evacuated from the kegs?

Never have, of course I'm a clean fanatic. There is no distinguishable hop aroma in my fermenter before I sanitize it.

 

[BasementArtie]

Never have, of course I'm a clean fanatic. There is no distinguishable hop aroma in my fermenter before I sanitize it.

I really don't understand how my Starsan then smell hoppy and/or of other fermentation characteristics after one fermentation co2 keg purged when no one else seems to experience it.

I also meticulously clean the kegs manually dismantling them every time. Then using an alkaline brewery cleaner, rinse, then using beer/milk stone cleaner at repassivation levels, rinse, then new Starsan filling the vessel. I never have any aromas in the clean keg before use. No residue. The vessel essentially looks and smells brand new inside each time. Fermenter cleaned in an very similar way. Also all closed lines are cleaned with beer line cleaner, rinsed, starsaned then purged with CO2 before use.

 

[mashdar]

I don't think it's surprising that hot fermentation gas makes it smell like hops*. Particularly if you're doing dry yeast or lager with a slower start (more contact time.)

A lot of people don't have the issue because they're just sanitizing a keg, emptying it, and then hooking it up to ferm gas (with an air lock or spunding valve on outlet)

Do you get something out of pushing 5 gallons of star san?

*edit: but if it doesn't raise pH and the star san still foams like crazy (surfactant in tact), then it probably doesn't matter.

 

[Crafty_Brewer]

I don't think it's surprising that hot fermentation gas makes it smell like hops*. Particularly if you're doing dry yeast or lager with a slower start (more contact time.)

A lot of people don't have the issue because they're just sanitizing a keg, emptying it, and then hooking it up to ferm gas (with an air lock or spunding valve on outlet)

Do you get something out of pushing 5 gallons of star san?

*edit: but if it doesn't raise pH and the star san still foams like crazy (surfactant in tact), then it probably doesn't matter.

Supposedly pushing starsan out is more effective in creating a very low O2 environment than just using gas to diffuse/purge the air out.